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Date: Sat, 23 May 2015 18:53:19 +0200
From: Max Reitz <mreitz@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH v6 05/13] virtio-blk: Don't handle output
 when there is "device IO" op blocker
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To: Fam Zheng <famz@redhat.com>, qemu-devel@nongnu.org
Cc: Kevin Wolf <kwolf@redhat.com>, qemu-block@nongnu.org, jcody@redhat.com, armbru@redhat.com, Stefan Hajnoczi <stefanha@redhat.com>, amit.shah@redhat.com, pbonzini@redhat.com

On 21.05.2015 08:42, Fam Zheng wrote:
> virtio-blk now listens to op blocker change of the associated block
> backend.
>
> Up on setting op blocker on BLOCK_OP_TYPE_DEVICE_IO:
>
>    non-dataplane:
>     1) Set VirtIOBlock.paused
>     2) In virtio_blk_handle_output, do nothing if VirtIOBlock.paused
>
>    dataplane:
>     1) Clear the host event notifier
>     2) In handle_notify, do nothing if VirtIOBlock.paused
>
> Up on removing the op blocker:
>
>    non-dataplane:
>     1) Clear VirtIOBlock.paused
>     2) Schedule a BH on the AioContext of the backend, which calls
>     virtio_blk_handle_output, so that the previous unhandled kicks can
>     make progress
>
>    dataplane:
>     1) Set the host event notifier
>     2) Notify the host event notifier so that unhandled events are
>     processed
>
> Signed-off-by: Fam Zheng <famz@redhat.com>
> ---
>   hw/block/dataplane/virtio-blk.c | 25 ++++++++++++++++-
>   hw/block/virtio-blk.c           | 59 +++++++++++++++++++++++++++++++++++++++--
>   include/hw/virtio/virtio-blk.h  |  8 +++++-
>   3 files changed, 88 insertions(+), 4 deletions(-)

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Reviewed-by: Max Reitz <mreitz@redhat.com>